Ok first i'll do the DC's instructions and why.
Right all there menatallity is the same right through the back 4 quite defensive, reason for this is i dont want them to attack the ball too early and get cought out by an opposition attacker, that is what by DMC who drops back is for he covers that area of the pitch.
Also there all on mixed passing as i dont want them to be to rigid by saying you must pass it short, which could get u in trouble, if they need to go long they can do. I dont want a Sol Campbell defender either who gets forward there duties are defending and thats it, part from corners.
Full backs!
Right same mentallity as the DC's so they work in a group together, these are occasionally allowed to get forward, thats why there setting for forward runs is on mixed, i've also give them through balls as when they work with the wingers forward runs, it sets up attacks quite quickly.
They also cross from deep as i dont want them to go to the byline, as if i lost the ball they have a better chance of getting back, also i make sure the wingers mentallity isn't to high as the gap between my full backs and wingers would be too much, and they need to work together.
Also note my creative freedom is far down as much as possible for my back 4, i dont want them to do anything silly so i give them basic instructions nothing complicated and hope they follow it.
right the DMC insructions, same mentallity as the defenders, but hard tacking as he needs to get stuck in, also no creative freedom, as i want him to perform similarly to Makelele at Chelsea, i.e no nonsense.
The mistake alot of people make with a DMC is they put closing down on full, this to me is a huge mistake, as they get dragged out of position, where as you want them to sit in front of the back 4.
Target man, i've put him in, because he is an integral part of my teams defence, his mentallity is only normal, this is so he playes deeper then the other striker, and doing so wins alot of the 50/50 balls in the middle of the park.
Alot of goals conceeded or created come from balls won in the centre circle, for goal kicks from either team this is where i want this player winning the things in the air.
I come to these conclusions after watching many games on full view and analysing every bit of the game, i.e headers won and lost, and then work out how i can turn this into my favour.
With the tactic i use, i feel though that it defends right through the team, and by that i mean making them as compact as possible, to reduce space and make less passes go astray, keep a watch for headers won and lost and get your big guns in the right area contesting them.
Good luck with your tactic, hope this helps!